/Engine/Source/Runtime/RenderCore/Public/ShaderCodeArchive.h
We decompression, group, and recompress shaders when they are added to iostore containers in UnrealPak, where we don't have access to cvars - so there's no way to configure - so we force Oodle and allow specification of the parameters here.
namespace ShaderCodeArchive { bool ShaderCodeArchive::CompressShaderWithOodle ( uint8 * OutCompressedShader, int64 & OutCompressedSize, const uint8 * InUncompressedShaderCode, int64 InUncompressedSize, [FOodleDataCompression::ECompressor](API\Runtime\Core\Compression\FOodleDataCompression__ECompress-) InOodleCompressor, [FOodleDataCompression::ECompressionLevel](API\Runtime\Core\Compression\FOodleDataCompression__ECompress-_1) InOodleLevel ) }